<!DOCTYPE HTML>
<html>

<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <title>函数调用</title>
  <script type="text/javascript">
    function contxt() //定义函数
    {
      alert("哈哈，调用函数了!");
    }
  </script>
</head>

<body>
  <form>
    <input type="button" value="点击我" onclick="contxt()" />
  </form>
</body>

</html>